'Flawless' diamond the size of a squash ball sells for 3million

Glistening on every one of its 92 facets, this 101.2-carat diamond set an auction house alight yesterday.

The stone, which is the size of a ping-pong ball, is the largest colourless diamond to appear at auction in 18 years, Christie's said - and had a price tag to match.

Set in a tiara rather than a pendant because it is so thick, it is one of only four colourless diamonds of more than 100 carats ever to come up for sale.

Trying on the diamond tiara

Trying on the diamond tiara

It was bought for £3million by a first-time auction buyer from Hong Kong, with a telephone bid. The new owner will have the right to name the diamond.

Francois Curiel, the auctioneer, said: 'The atmosphere in the room was very excited.' Internally flawless, the stone was cut from a 460-carat rough diamond. It was discovered in South Africa's biggest diamond mine, Premier Mine, and was on exhibition in London in February before the auction in Hong Kong. The world's largest rough diamond, the Cullinan Diamond, was found in the same mine.

The value of a stone is based on clarity and size. Coloured diamonds are graded on a different scale.

A carat is a fifth of a gram. The record price for a gem was £8.25million paid for the

100.1-carat Star of the Season colourless diamond in 1995.

A giant diamond the size of a squash ball was sold at auction yesterday for £3 million.

The 101.27-carat stone is the largest colourless gem to be sold in Asia.

The diamond, which is internally flawless was sold after patchy bidding.

Set in a tiara, the diamond is one of only four colourless diamonds of over 100 carats to have come up for sale.